Pneumatically actuated stapling plier

ABSTRACT

A pneumatically actuated stapling plier device including a generally L-shaped cylinder member actuated by a piston mounted in cylinder positioned in the rearward end of the tubular part of the housing structure defining the handle portion thereof, the arrangement of the clincher member and its driving piston rendering the device less bulky and easier to handle and eliminating external connecting rods heretofore provided which are subject to damage during use. The device includes a sequencing valve operable to sense predetermined pressure conditions established in the clincher cylinder by the operation of a manually actuated valve to sequentially operate a main valve controlling the communication of reservoir pressure with the drive cylinder thereby insuring a sequential cycle of operation of the clincher arm and staple driving element in which the workpiece is compressed prior to the driving and clinching of the staple therethrough.

0 United States Patent 1 [11] 3,734,378 Rice et al. [451 May 22, 1973 [54] PNEUMATICALLY ACTUATED Primary Examiner-Granville Y. Custer, Jr.

STAPLING PLIER Anomey-Cushman, Darby & Cushman [75] inventors: Joseph A. Rice, Swansea, Mass; Ed-

ward I. Fisher, Westerly, RI. [57] ABSTRACT [73] Assi nee Textron Inc Providence R I A pneumatically actuated stapling plier device includg ing a generally L-shaped cylinder member actuated by [22] Filed: Sept. 2, 1971 a piston mounted in cylinder positioned in the rear- I 7 ward end of the tubular part of the housing structure [21] Appl No 177's 0 defining the handle portion thereof, the arrangement of the clincher member and its driving piston render- [52] U.S.Cl ..227/124, 227/130 ing th device less bulky and easier to handle and lI-lt- Cl. eliminating external connecting rods heretofore pro- Fleld of Search t vided are subject to damage during use The 227/144, 155 device includes a sequencing valve operable to sense predetermined pressure conditions established in the l Referell? cued clincher cylinder by the operation of a manually actu- UNITED STATES PATENTS ated valve to sequentially operate a main valve controlllng the communication of reservoir pressure with 2,687,522 8/1954 .luilfs ..227/l24 the drive cylinder thereby insuring a sequential cycle 3,397,823 8/1968 Volkmanfl v 127/124 of operation of the clincher arm and staple driving ele- 3,580,458 5/1971 Monacelll ..227/124 ment in which the workpiece is compressed -i to the driving and clinching of the staple therethrough.

9 Claims, 4 Drawing Figures /00 4 74 5e 9? 90 969/ 58 7 ,0 34 4///////// 6 2\ 36 //0 g6 54 '0 9 //2 64 /0 42 50 48 8 0 as g: 102 78 x05 d C A85 /:5'6 81; 3 we 3a l 2e 25 r h. 2 34 A2 24 22 5' /5'0 I52 4- M0 44 M0 20 I46 4 -42 Patented May 22, 1973 5 Sheets-Sheet l e w M M p 9 MW, Z L M vw QN mm W|fi\ m WV 0. VW v.0 Wm

Patented May 22, 1973 3,734,378

3 She eta-Sheet 2 INVENTORS ATTORNEYS PNEUMATICALLY ACTUATED STAPLING PLIER This invention relates to pneumatically actuated stapling pliers and more particularly to an improved arrangement of the component parts of such devices rendering the device easier to handle, less bulky and less subject to damage during use.

Pneumatically actuated stapling pliers are wellknown in the art. Devices of this type are disclosed in the following u.S. Pat. Nos. 2,687,522; 2,943,327; 3,397,828; and 3,580,458. These conventional devices include a rigid housing structure providing a nose portion defining a staple drive track, a drive portion disposed vertically above the nose portion providing a lower drive chamber within which a piston and driver assembly is reciprocably mounted and an upper concentric chamber within which a piston and piston rod assembly is reciprocably mounted, the housing structure includes a handle portion extending rearwardly from the drive portion which is disposed in upwardly spaced relation to a staple magazine assembly extending rearwardly from the nose portion of the housing.

The upper piston and piston rod assembly is provided for the purpose of effecting movement of a clincher arm disposed below the magazine assembly into a position adjacent the end of the drive track so as to compress a loose ply workpiece therebetween just prior to the movement of the staple driver through its work stroke to drive a staple fed to the drive track by the magazine assembly outwardly of the drive track through the compressed workpiece and into clinching relation to the clinching arm. In the conventional prior art devices, the actuating piston rod extends upwardly through an appropriate opening in the upper end of the drive portion of the housing and an external connecting rod or rods is mounted between the upper end of the piston rod and a horizontally extending arm fixed to the clincher arm. In some instances the clincher arm, which together with the actuating arm is of generally U-shaped configuration defining a workpiece receiving throat, is pivotally mounted on the housing adjacent the rearward lower portion thereof. In other instances the clincher arm is fixed with respect to the actuating arm and connecting rod, the entire rigid external assembly being mounted for vertical sliding movement.

While these conventional devices provide generally satisfactory operation, the provision of the upper actuating piston and piston rod unit, the external connecting rod or rods extending downwardly to the actuating arm associated with the clincher arm necessitates a relatively high profile, introduces forward imbalance to the tool and presents external moving parts which are dangerous to the operator and subject to damage during use.

It has been proposed in the prior art (see German Patent No. 1,174,296) to alleviate the high profile problem by mounting the piston and piston rod assembly rearwardly adjacent the drive chamber. However, an arrangement of this type does not affect the forward imbalance nor does it eliminate the provision of external connecting rods.

Accordingly, it is an object of the present invention to provide a pneumatically actuated stapling plier which embodies an improved arrangement of component elements including an actuating piston directly connected with the upwardly extending free end of a generally L-shaped clincher member so as to permit the device to have a low profile, a better balance and feel when supported in the hand of an operator and permitting elimination of the externally mounted connecting rods heretofore provided in devices of this type.

Another object of the present invention is the provision of a device of the type described in which the actuating arm of the clincher member is disposed between a pair of depending mounting arms forming a part of the rigid housing structure so as to minimize the exposed external moving parts of the device to include only the movable clincher arm.

Still another object of the present invention is the provision of a device of the type described having improved pneumatic circuitry for sequentially effecting the movement of the clincher arm and staple driving element through successive operative cycles.

Still another object of the present invention is the provision ofa device of the type described which is simple in construction, effective in operation and economical to manufacture and maintain.

These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.

The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.

In the drawings:

FIG. 1 is a vertical sectional view of a device embodying the principles of the present invention, showing the parts in their normal inoperative position preparatory to an operative cycle;

FIG. 2 is a view similar to FIG. 1 showing the parts in a position at the end of the drive stroke of the operative cycle;

FIG. 3 is a top plan view of the device of the present invention; and

FIG. 4 is a rear elevational view of the device of the invention.

Referring now more particularly to the drawings, there is shown therein a stapling plier device, generally indicated at 10, embodying the principles of the present invention. In the drawings the device is shown positioned to drive a staple through a work piece disposed horizontally. It will be understood that the device is portable and thus capable of stapling work pieces disposed in any position including the horizontal position shown. For convenience, the device will be described in relation to the illustrated operative position, and consequently, terms such as horizontal," vertical, above, below," forward, rearward, etc. are to be construed in their relative sense.

The device 10 comprises a rigid housing structure 12 including a nose portion provided by a nose piece 14 having internal surfaces defining an elongated drive track 16. Secured to the nose piece 14 and extending rearwardly therefrom is a staple magazine assembly 18, which may be of any conventional design, adapted to receive a supply of staples in the form of a staple stick and to feed successive leading staples of the stick forwardly into the drive track to be driven outwardly thereof by a staple driving element 20. The staple driving element 20 is slidably mounted in the drive track 16 for movement through successive operative cycles including a drive stroke during which the leading staple fed forwardly into the drive track is driven outwardly thereof and a return stroke.

The staple driven outwardly of the drive track 16 by the staple driving element 20 is adapted to be moved into piercing relation through a loose ply workpiece and then clinched during the drive stroke of the fastener driving element. In order to effect the clinching action and to compress the loose ply workpiece prior to the piercing action, there is provided a clincher member, generally indicated at 22, which is mounted on the housing structure 12 for movement from a workpiece receiving position through an operative stroke toward a clinching position and from the clinching position through a return stroke into its workpiece receiving position. The movement of the clincher number 22 is timed with respect to the movement of the staple driving element so that the operative stroke of the former and the drive stroke of the latter occur sequentially to thereby insure that the clincher number 22 will be in its clinching position compressing the workpiece as the staple is moved outwardly of the drive track by the staple drive element 20, In this way, a proper piercing and clinching action of the staple within the workpiece is secured.

In accordance with the principles of the present invention, this sequential cycling is obtained by controlling the communication of a source of air under pressure, suitably connected with the device 10, with a first cylindrical chamber 24 formed in the upper rearward portion of the housing structure 12 with its axis extending generally horizontally and having a piston member 26 slidably mounted therein for effecting the operative stroke of the clincher member and a second cylindrical drive chamber 28 formed in the portion of the housing structure 12 disposed above the nose piece 14 with its axis extending generally vertically and having a drive piston 30 slidably mounted therein for effecting the drive stroke of the staple driving element 20.

The control of the air pressure can be accomplished in any known manner, preferably however, the system shown is utilized which generally includes a manually operable valve assembly, generally indicated at 32, for directly controlling the communication of the source of air under pressure with the clincher cylinder 24, a pilot pressure operated main valve assembly, generally indicated at 34, for controlling the communication of the source of air under pressure with the drive cylinder'28 and a sequencing valve assembly, generally indicated at 36, operable to sense a predetermined pressure condition associated with pressurization of the clincher cylinder 24 and to establish an actuating pilot pressure in association with the main valve assembly 34.

In the preferred embodiment shown, the housing structure 12 is comprised of several rigidly interconnected parts, the largest of which is in the form of a main casting within which the various valve assemblies and cylinder and piston units are housed. The nose piece 14 and certain fixed members of the magazine assembly 18 are properly regarded to be component parts of the housing structure. While these parts are shown as being separate from the main casting, it is clearly within the contemplation of the present invention that all or portions of these parts may be provided as integral portions of the main casting. Likewise, integral parts of the main casting may be provided by separate fixedly interconnected parts.

in the preferred form shown in the drawings, the main casting includes a forward drive part or portion 38 extending vertically above the nose piece 14, a tubular part 40 extending rearwardly from the drive portion 38 in vertically spaced relation to the magazine assembly l8 and a rearward part, in the form of a pair of generally parallel arms 42, extending vertically downwardly from the rear end of the tubular part 40 in embracing relation to the magazine assembly 18.

As shown, the drive portion 38 is hollow and open at its lower end to receive upwardly therein a cylinder member 44, the interior surface of which defines the drive chamber 28. The upper end of the cylinder member engages a washer 46, or resilient material, disposed upwardly against an interior horizontal wall portion 48 forming a part of the main casting. The cylinder member is retained in engagement with the washer by the nose piece 14 which is detachably fixedly connected with the main casting, as by bolts or the like (not shown). The wall portion 48 is provided with a central opening 50 which communicates with a horizontally extending cavity 52 formed within the main casting adjacent the juncture between the drive portion 38 and the tubular part 40.

Mounted within the cavity 52 is a series of tubular inserts 54, 56, 58, and 60. The forward or outermost insert 54 constitutes a cap element which is detachably fixedly connected with the main casting as by bolts or the like (not shown), the cap having discharge exhaust openings 62 extending laterally therethrough. The insert 56 is disposed in abutting relation to the forward insert 54 and a horizontal bore 64 extending therethrough which communicates with the discharge openings 62 in the cap insert 54. The inner end of the bore 64 has a counterbore 66 formed therein, the lower inner end portion of which is communicated with the central opening 50 by a radially extending opening 68. The rearward portion of the counterbore 66 is formed with a frusto conical surface providing a valve seat adapted to be engaged by an annular valve element 70 carried by a valve member 72 forming a part of the main valve assembly 34. The valve member 72 includes a forwardly extending stem portion having an annular valve element 74 mounted in the forward extremity thereof which is adapted to engage a frusto conical surface defining a valve seat formed in the forward portion of he valve insert bore 62.

The rearward or innermost insert is, as shown, in the form of a flanged piston like element, the flanged end of the insert engaging an apertured wall portion of the main casting defining the inner end of the recess. The forwardly adjacent insert 58 is formed with an axially extending central bore having a counter bore 76 formed in the forward end portion thereof and a pair of counterbores 78 and 80 formed in the rearward end portion thereof. The lower forward end portion of the insert 58 is cut away so as to communicate the counterbore 76 with a transverse opening 82 formed in the wall of the main casting defining the recess 52. The opening 82 communicates with the hollow interior of the tubular part 40 of the housing structure, which defines a reservoir 84 for receiving air under pressure from the source (not shown) through an airline having an end fitting (not shown) adapted to be threadedly engaged with a threaded .bore 86 formed in the upper rearward end of the tubular housing part 40.

The valve member 72 also includes a piston portion 88 disposed rearwardly of the valve element having an annular groove formed in the periphery thereof receiving an O-ring seal which slidably engages the inner peripheral surface of the counterbore 76. The portion of the counterbore 76 extending rearwardly of the seal of the piston portion 88 constitutes a pilot chamber arranged to be charged with reservoir pressure. As shown, the air under pressure flowing from the reservoir 84 into the forward end of the counterbore 76 through opening 82, is continuously restrictingly communicated to the pilot chamber as by a restricted orifice 90 extending radially inwardly of the valve member 72 between the valve element 70 and piston portion 88 into a counterbored opening 92 formed in the rearward end portion of the valve member 72.

The high pressure air in the pilot pressure chamber 76 is exhausted to atmosphere through an exhaust passageway provided by a plurality of circumferentially spaced holes 94 extending from the forward end of counterbore 78 into an annular groove formed in the adjacent periphery of insert 58 and an opening 96 formed in the adjacent exterior wall of the main casting in communication with the annular groove. The exhaust of the pilot pressure is controlled by the sequencing valve assembly 36 which includes a valve member 98 carrying an annular valve element 100 of resilient material or the like having a rearward surface adapted to engage a valve seat provided by the centrally bored forwardly extending surface defining the inner end of counterbore 76.

The valve member 98 includes a forward extending stem portion which engages within one end of a coil spring 102 the opposite end of which is engaged within the rearward opening 92 of the valve member 72. The valve member 98 also includes a rearwardly extending stem portion which is slidably mounted within an axial bore formed in the forward end portion of a pressure sensing member 104. The rearward portion of the member 104 is in the form of a piston slidably engaged within the counterbore 80 and sealed with respect thereto as by an O-ring seal or the like. The forward portion of the member 104 is in the form ofa piston rod slidably mounted within the counterbore 78 and similarly sealed with respect thereto as by an O-ring seal or the like.

The exterior periphery of the pressure sensing member 104 between the seals in the forward and rearward portions thereof define with the coextensive interior periphery of the insert 58, a pressure chamber which is continuously communicated with the reservoir 84 through a passageway provided by a plurality of circumferentially spaced holes 106 extending from the forward end of counterbore 80 into an annular groove formed in the exterior periphery of the insert and an opening 108, formed in the wall portion of the main casting defining the recess 52, communicating the annular groove with the reservoir. In order to prevent escape of high pressure air from the reservoir through the discharge opening 96, suitable sealing means in the form of O-ring seals or the like are provided in the periphery of the insert 58 on opposite sides of the exhaust passage annular groove.

The rearward surface of the pressure sensing member 104 is adapted to engage the forward surface of the insert 60, the latter being sealingly engaged within the counterbore 80, as by an O-ring seal or the like. The interior periphery of the counterbore 80 between the seal of the insert 60 and the rearward seal of the member 104 defined with the adjacent ends of the latter a pressure chamber into which the pressure condition sensed by the pressure sensing member 104 is communicated.

In the preferred embodiment shown, the pressure condition sensed is the pressure established within the clincher chamber 24 to effect movement of the clincher member from its workpiece receiving position toward its clinching position. In this regard, it will be noted that the chamber 24 is formed as a rearwardly opening recess by a wall portion 110, constituting an integral part of the main casting, disposed below the threaded air inlet bore 86. Any suitable means may be provided for communicating the clincher chamber to the pressure chamber for actuating the sequencing valve assembly 36 and, as shown, there is provided a length of hose or flexible tubing 112 having one end thereof secured, as by a conventional fitting or the like within an axial bore in the insert 60 and the other end thereof secured, as by a conventional fitting or the like, within an aperture extending through the wall portion 110.

In the embodiment shown, the clincher chamber 24 and piston 26 constitute a single acting unit which is operable by air under pressure to effect the operative stroke of the clincher member 22. While it will be understood to be within the contemplation of the present invention to render the unit double acting, with the single acting arrangement shown, the return stroke of the clincher member is accomplished by spring return means 114.

As best shown in FIG. 4, the clincher member 22 is preferably constructed as a rigid assembly including a generally horizontal clinching arm 116 in the form of a metal stamping having an inverted U-shaped crosssectional configuration which tapers forwardly from its rear end and has a clinching anvil 118 mounted on the upper surface of the forward end thereof. Fixedly secured to the rearward end of the arm 116, as by welding or the like, is the lower end of a pair of plates, defining an actuating arm 120. The arm plates 120 extend upwardly between the housing arms 42 in embracing relation to the magazine assembly 18 and then angle inwardly until disposed in abutting relation. The butting upper end portions of the arm plates extend upwardly through a slot 122 formed in the lower rearward portion of the wall portion and are bent into horizontally extending socket formation within which an adjustable bolt 124 is threadedly mounted. The head of the bolt 124 engages within a recess formed in the rear of the piston 26 so as to transmit the rearward motion of the piston 26 through its operative stroke to the upper end of the actuating arm of the clincher member 22. As shown, the open end of the clincher chamber 24 may be closed by a spring finger dust cap 125 or the like.

The clincher member 22 is pivotally connected to the housing structure 12 as by a pivot pin 126 extending through the lower ends of the housing arms 42 and the arm plates 120 at a position just above the rearward end of the clinching arm 116. The spring return means 114 is preferably in the form of a pair of parallel coil springs mounted with their rear ends in engagement with a cross bar 128 extending integrally across the rearward edges of the housing arms 42 at a position below the magazine assembly. The forward ends of the springs 114 are connected in abutting relation to a cross bar 130 welded to the forward edges of the arm plates 120. The housing cross bar 128 serves the multiple purpose of strengthening the arms 42, supporting the return springs 114 and supporting the rearward end portion of the magazine assembly 18.

The manually operable valve assembly 32 is operatively positioned between the reservoir 84 and the clincher chamber 24. As shown, the valve assembly 32 includes a valve insert 132 mounted within a bore 134 formed in the lower forward portion of the housing tubular part 40. Mounted within the insert 132 is a valve member 136 having an annular valve element 138 carried by the upper end thereof for engagement with an upwardly facing valve seat 140 formed in the upper portion of the valve insert in communication with the reservoir 84. The valve insert 132 is formed with a central rearwardly extending opening 142 which communicates with the forward end of the chamber 24 as by a passageway 144 formed integrally within the lower wall portion forming the tubular housing part 40. In this regard, it will be noted that the exterior surface of the central portion of the tubular housing part 40 is configured so as to provide a handle portion to be gripped by the operator.

A trigger member 146 is pivotally mounted on the housing structure 12, at a position indicated at 148, so that when depressed upwardly by a digital pressure of the operator, the trigger member will engage the lower end of the valve member 136 and move the same upwardly, thus moving the valve element 138 away from the seat 140 and permitting the air under pressure within the reservoir 84 to enter the clinching chamber 24 through opening 142 and the passageway 144. When the trigger is released, the pressure acting on the upper end of the valve member, as well as its own weight, will move the latter downwardly into a position wherein the valve element 138 engages the seat 140. In this position, air under pressure within the clincher chamber 24 is communicated to an exhaust outlet 150 extending transversely through the tubular part 40 into communication with the bore 134. The insert 132 is provided with a forwardly extending opening 152 which communicates exteriorly with the exhaust outlet 150 and interiorly with the opening 142.

The valve member 136 includes a lower end portion 154 of an enlarged diameter to closely engage within the bore of the insert. The enlarged portion 154 is disposed below the opening 152 when the valve member 136 is disposed in its normally inoperative and closed position, thereby permitting communication between the openings 142 and 152. When the valve member 136 is moved into its operative open position, the enlarged portion 154 serves to close off communication between lateral openings 142 and 152. In accordance with conventional practice, the valve insert 132 is retained within a bore 134 as by a cross pin or the like and the escape of high pressure fluid between the insert and bore is prevented by the utilization of a pair of O- ring seals or the like.

The main valve assembly 34 serves to communicate reservoir pressure with the upper end of the drive chamber 28 when the main valve member 72 is moved from its normally closed position into an open position. Communication of the drive chamber 28 with reservoir 84 serves to effect the drive stroke of the piston 30. The return stroke of the piston, in the preferred embodiment shown, is effected by a conventional plenum chamber system. While such a return system is preferred, it will be understood that any of the well known methods of effecting the drive piston return stroke may be utilized if desired.

As best shown in FIGS. 1 and 2, the plenum chamber return system includes a plenum chamber 156 which is disposed in surrounding relation to the cylinder member 44. The plenum chamber 156 communicates with the drive chamber 28 by a series of upper inlet openings 158 and a series of lower outlet openings 160. In the embodiment shown, piston 30 is provided with a depending resilient bumper element 162 which is adapted to engage the upper surface of the nose piece 14 when the piston reaches the end of its drive stroke. The inlet openings 158 are disposed in a vertical position such that they will be communicated with the portion of the chamber 28 disposed above the piston seal when the bumper 162 is in engagement with the nose piece 14. Thus, in accordance with conventional practice, the pressure within the upper portion of the chamber acting on the piston to effect its drive stroke is communicated with the plenum chamber 156 at the end of the drive stroke. The openings 160 are disposed below the openings 158 so as to communicate the pressure within the plenum chamber to the annular space below the piston defined by the lower periphery of the bumper 162 and the piston seal. In accordance with conventional practice, when main valve member 72 is moved into its close position, the upper end of the drive chamber 28 is exhausted to atmosphere permitting the plenum chamber pressure acting on the lower annular surface of the piston to effect the return stroke. Also, in accordance with conventional practice, a restricted clearance is provided by the nose piece 14 around the staple driving element so as to permit the return air to dissipate to atmosphere through the drive track 16 after the seal provided by the bumper 162 is broken during the initial portion of the return stroke.

It can thus be seen that by mounting the clincher member 22 and its actuating piston 26 on the frame structure 12 in the manner described, a highly favorable weight distribution of the component parts of the device 10 is secured. This weight distribution renders the present device 10 easier to handle in comparison with prior art devices where the actuating piston for the clincher member is positioned in alignment with the main drive piston adjacent the forward portion of the frame structure. Moreover, with the present arrangement, the external connecting rods heretofore provided in the prior art devices are eliminated. Consequently, the maintenance problem resulting from damage to such parts during use is eliminated. In the preferred embodiment of the present invention, the mounting arms 42, which form an integral part of the main casting of the frame structure 12, serve to protect the actuating arm of the clincher member so that the only exposed moving part of the device is the clincher arm itself which, due to its arrangement, provides a highly desirable deep throat for receiving the workpiece. In addition, by providing a main valve assembly 34 which is movable forwardly and rearwardly in a position above the drive chamber 28, the profile of the device can be minimized in terms of its height. This minimization of the height profile is desirable and permits the present device to operate with a wide variety of workpiece configurations in confined areas.

The provision of a sequencing valve assembly 36, which senses the pressure in the clincher pressure chamber 24 and sequentially controls the operation of the main valve assembly 34 insures that the operating cycles of the clincher arm 116 and staple driving element will be performed in sequential fashion whereby the workpiece is compressed prior to driving and clinching the staple therethrough. It is believed that the operation of the device whereby this sequential operation is obtained is apparent from the above description. However this operation will be briefly summarized below.

Prior to the communication of a source of air under pressure with the device, the position of the parts is as shown in FIG. 1. In this regard, it will be noted that spring 102 serves to maintain the main valve member 72 in its closed position. The size of the orifice 90 is such that upon the initial communication of a source of air under pressure with the reservoir 84, the pressure differential across the orifice does not build up sufficiently to overcome the force of the spring 102, thus insuring against inadvertent actuation upon initial connection of the device with the source of air under pressure.

Normal operation is initiated by the operator depressing the trigger 146 which causes the valve member 136 to move into its opened position communicating the reservoir 84 with the clincher chamber 24 to drive the piston 26 rearwardly. The clincher member 22 is thus moved into the clinching or compressing position, as shown in FIG. 2, against the action of spring 114, to compress a loose ply workpiece disposed within the throat of the device. The compression of the workpiece arrests the movement of the clincher member 22 causing a pressure build-up within the clincher chamber 24 which is sensed within the chamber 80 by virtue of the communication provided by tubing 112. Since the pressure within the chamber 80 acts upon the greater rearwardly facing pressure area of the member 104 than the reservoir pressure acting on the annular forwardly facing portion thereof, the sensing valve member 98 will move forwardly into the position shown in FIG. 2 disengaging the valve element 100 from its valve seat and exhausting the pilot chamber 76 to atmosphere through openings 94 and 96. The exhaust of the pilot chamber 76 establishes a pressure differential across the piston element 88 which overcomes the bias of spring 102 causing the main valve member 72 to move rearwardly into its open position, as shown in FIG. 2, thus communicating reservoir 84 with the upper end of the drive chamber 28 through openings 82 and 50 to commence the drive stroke of the staple driving element 20.

Upon release of the trigger 146, the valve member 136 is moved into its closed position thus exhausting the clincher chamber 24 to atmosphere through the exhaust port 152 and permitting the clincher member 22 to move back into its opened position under the action of springs 114. The exhaust of the pressure chamber-24 is sensed within the chamber 80 permitting reservoir pressure acting on the annular surface of the member 104 to move the sequencing valve member 98 rearwardly into a position closing the exhaust for the pilot chamber 76. As valve element 100 closes the pilot chamber 76, the pressure build-up therein effects movement of the main valve member 72 into its closed position thus exhausting the drive chamber 28 to atmosphere through outlet ports 62. The return stroke of the drive piston 30 and staple driving element 20 is effected through the conventional operation of the plenum chamber return system.

It thus will be seen that the objects of this invention has been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiment has been shown and described for the purpose of illustrating the functional and structural princi-' ples of this invention and is subject to change without departure from such principles. Therefore, this inven' tion includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

l. A device for tightly plying a loose ply workpiece and for driving and clinching a staple therethrough, comprising:

a rigid housing structure including a nose portion having means therein defining a vertically extending drive track,

a magazine assembly extending rearwardly of said nose portion for receiving sticks of staples and for feeding successive leading staples of a stick forwardly into said drive track,

said rigid housing structure further including a drive portion disposed above said nose portion and having means therein defining a cylindrical drive chamber disposed with its axis extending vertically,

a drive piston mounted within said cylindrical drive chamber for movement through successive operative cycles including a downward drive stoke and an upward return stroke,

a staple driving element slidably mounted within said drive track and operatively connected with said drive piston for movement thereby through a drive stroke in response to thedrive stroke of said piston to drive a staple in said drive track outwardly thereof and through a return stroke in response to the return stoke of said piston,

said housing structure also including an upper tubular part extending rearwardly from said drive portion, said tubular part including a forward portion adjacent the drive portion disposed in vertically spaced relation to said magazine assembly providing a handle adapted to be manually gripped by an operator,

a generally L-shaped plier member including an actuating arm extending generally vertically upwardly from a position below the rearward end portion of said magazine assembly and a clincher arm extending generally forwardly from the lower end of said actuating arm in a position below said magazine assembly and said nose portion to define therewith a forward open throat for receiving a loose ply workpiece therein,

means mounting said L-shaped plier member on said rigid frame structure for pivotal movement about a horizontally extending transverse axis disposed adjacent the juncture between said arms between first and second limiting positions,

said clincher arm having staple clincher anvil means on the upper surface of the forward free end portion thereof disposed in spaced relation to the end of said drive track when said L-shaped plier member is disposed in said first position and movable therewith along a path generally aligned with said drive track into adjacent relation to the end of said drive track when said L-shaped plier member is moved into said second position,

said tubular part having means therein defining a pressure chamber in the rearward end portion thereof,

an actuating member mounted in said pressure chamber for movement through a rearward operative stroke in response to the communication of air under pressure with said pressure chamber and for movement through a forward return stroke in response to the communication of said pressure chamber to atmosphere,

means connecting said actuating member with the upper free end portion of said actuating arm to effect movement of said L-shaped plier member from said first position toward the second position thereof in response to the operative stroke of said actuating member,

said tubular part also having means therein defining a reservoir for receiving and containing air under pressure supplied thereto from a source of air under pressure, and

manually controlled means carried by said housing structure operable (l) to communicate said reservoir sequentially with said pressure chamber and said cylindrical drive chamber respectively to thereby initially move said clinching anvil means toward the end of said drive track to compress a loose ply workpiece disposed in said throat and then to move said staple driving element through its drive stroke to drive a staple through the compressed workpiece and clinch the same against said clinching anvil means and (2) to communicate said chambers to the atmosphere to permit said staple driving element and said actuating member to move through their return strokes.

2. A device as defined in claim 1 wherein said rigid housing structure includes a main casting of unitary construction providing said drive portion, said tubular part and a pair of spaced arms extending downwardly from the rearward end of said tubular part on opposite sides and below the adjacent portion of said magazine assembly, said actuating arm including a bifurcated lower end portion disposed substantially between said housing arms and extending downwardly on opposite sides and below said adjacent magazine assembly portion, said plier member mounting means including a pivot pin extending through said housing arms and said bifurcated end portion at a position below said adjacent magazine assembly portion.

3. A device as defined in claim 2 wherein said actuating arm includes an upper end portion extending through a slot formed in the rearward lower portion of said pressure chamber, and said actuating member and arm connecting means includes an adjustable element abuttingly engaging said actuating member and adjustably threadedly engaged within the upper end portion of said actuating arm.

4. A device as defined in claim 3 wherein said housing arms are formed with an integral strengthening element extending thereacross in a position rearwardly thereof and in supporting relation below said adjacent magazine assembly portion, said bifurcated end portion is provided with a fixed strengthening element extending thereacross in a position forwardly thereof and spring means mounted between said strengthening elements for effecting the return stroke of said actuating member and said plier member in response to the communication of said pressure chamber to atmosphere.

5. A device as defined in claim 4 wherein said tubular part has an opening formed in the rearward end thereof above said pressure chamber which communicates interiorly with said reservoir and is threaded to receive a fitting on the end of an air hose communicating at its other end with a source of air under pressure.

6. A device as defined in claim 5 wherein said manually controlled means includes main valve means mounted above said cylinder for forward and rearward movement between a first position communicating the upper end of said drive chamber with said reservoir to effect the drive stroke of said drive piston and a second position communicating the upper end of said drive chamber with the atmosphere to permit said drive piston to move through its return stroke, means defining a pilot chamber, said main valve means having a pilot pressure element movable therewith within said pilot chamber in response to predetermined changes of air pressure within said pilot chamber, manually controlled valve means movable in response to manual actuating from an inoperative position communicating said pressure chamber with the atmosphere into an operative position communicating said pressure chamber with said reservoir to effect the operative stroke of said pressure member and said clincher arm, and sequencing means operable in response to the establishment of a predetermined pressure condition within said pressure chamber following the communication thereof with said reservoir for effecting a change in the air pressure within said pilot chamber sufficient to effect movement of said main valve means into said first position to thereby effect the drive stroke of said drive piston in sequential relation with respect to the operative stroke of said clincher arm.

7. A device as defined in claim 6 wherein main valve means is movable into said first position in response to the exhaust of air pressure within said pilot chamber to atmosphere and into said second position in response to the establishment of a predetermined elevated air pressure therein, said sequencing means including sequencing valve means operable in one position to exhaust said pilot chamber and in another position to permit the establishment of said predetermined pressure therein, means defining a sensing chamber continuously communicating with said pressure chamber, said sequencing valve means having a pressure element movable within said sensing chamber in one direction to move said sequencing valve means into said one position in response to the establishment of an air pressure substantially equal to reservoir pressure within said pressure chamber and in the opposite direction to move said sequencing valve means into said other position in response to the exhausting of said pressure chamber to atmosphere.

8. A device as defined in claim 7 wherein said pilot chamber and said sensing chamber are cylindrical and disposed in spaced relation on a common axis which extends rearwardly.

9. A device as defined in claim 8 wherein said sensing chamber includes a fixed inner wall through which said sensing chamber is communicated with said pressure chamber, the pressure element being in the form of a piston having one side disposed in opposed relation to said inner wall and defining said sensing chamber therebetween and a piston rod extending from the other side of said piston, fixed wall means enclosing an annular space bounded by the exterior of said piston rod and the outwardly extending portion of said piston, and means for continuously communicating said annular space with said reservoir. 

1. A device for tightly plying a loose ply workpiece and for driving and clinching a staple therethrough, comprising: a rigid housing structure including a nose portion having means therein defining a vertically extending drive track, a magazine assembly extending rearwardly of said nose portion for receiving sticks of staples and for feeding successive leading staples of a stick forwardly into said drive track, said rigid housing structure further including a drive portion disposed above said nose portion and having means therein defining a cylindrical drive chamber disposed with its axis extending vertically, a drive piston mounted within said cylindrical drive chamber for movement through successive operative cycles including a downward drive stoke and an upward return stroke, a staple driving element slidably mounted within said drive track and operatively connected with said drive piston for movement thereby through a drive stroke in response to the drive stroke of said piston to drive a staple in said drive track outwardly thereof and through a return stroke in response to the return stoke of said piston, said housing structure also including an upper tubular part extending rearwardly from said drive portion, said tubular part including a forward portion adjacent the drive portion disposed in vertically spaced relation to said magazine assembly providing a handle adapted to be manually gripped by an operator, a generally L-shaped plier member including an actuating arm extending generally vertically upwardly from a position below the rearward end portion of said magazine assembly and a clincher arm extending generally forwardly from the lower end of said actuating arm in a position below said magazine assembly and said nose portion to define therewith a forward open throat for receiving a loose ply workpiece therein, means mounting said L-shaped plier member on said rigid frame structure for pivotal movement about a horizontally extending transverse axis disposed adjacent the juncture between said arms between first and second limiting positions, said clincher arm having staple clincher anvil means on the upper surface of the forward free end portion thereof disposed in spaced relation to the end of said drive track when said Lshaped plier member is disposed in said first position and movable therewith along a path generally aligned with said drive track into adjacent relation to the end of said drive track when said L-shaped plier member is moved into said second position, said tubular part having means therein defining a pressure chamber in the rearward end portion thereof, an actuating member mounted in said pressure chamber for movement through a rearward operative stroke in response to the communication of air under pressure with said pressure chamber and for movement through a forward return stroke in response to the communication of said pressure chamber to atmosphere, means connecTing said actuating member with the upper free end portion of said actuating arm to effect movement of said Lshaped plier member from said first position toward the second position thereof in response to the operative stroke of said actuating member, said tubular part also having means therein defining a reservoir for receiving and containing air under pressure supplied thereto from a source of air under pressure, and manually controlled means carried by said housing structure operable (1) to communicate said reservoir sequentially with said pressure chamber and said cylindrical drive chamber respectively to thereby initially move said clinching anvil means toward the end of said drive track to compress a loose ply workpiece disposed in said throat and then to move said staple driving element through its drive stroke to drive a staple through the compressed workpiece and clinch the same against said clinching anvil means and (2) to communicate said chambers to the atmosphere to permit said staple driving element and said actuating member to move through their return strokes.
 2. A device as defined in claim 1 wherein said rigid housing structure includes a main casting of unitary construction providing said drive portion, said tubular part and a pair of spaced arms extending downwardly from the rearward end of said tubular part on opposite sides and below the adjacent portion of said magazine assembly, said actuating arm including a bifurcated lower end portion disposed substantially between said housing arms and extending downwardly on opposite sides and below said adjacent magazine assembly portion, said plier member mounting means including a pivot pin extending through said housing arms and said bifurcated end portion at a position below said adjacent magazine assembly portion.
 3. A device as defined in claim 2 wherein said actuating arm includes an upper end portion extending through a slot formed in the rearward lower portion of said pressure chamber, and said actuating member and arm connecting means includes an adjustable element abuttingly engaging said actuating member and adjustably threadedly engaged within the upper end portion of said actuating arm.
 4. A device as defined in claim 3 wherein said housing arms are formed with an integral strengthening element extending thereacross in a position rearwardly thereof and in supporting relation below said adjacent magazine assembly portion, said bifurcated end portion is provided with a fixed strengthening element extending thereacross in a position forwardly thereof and spring means mounted between said strengthening elements for effecting the return stroke of said actuating member and said plier member in response to the communication of said pressure chamber to atmosphere.
 5. A device as defined in claim 4 wherein said tubular part has an opening formed in the rearward end thereof above said pressure chamber which communicates interiorly with said reservoir and is threaded to receive a fitting on the end of an air hose communicating at its other end with a source of air under pressure.
 6. A device as defined in claim 5 wherein said manually controlled means includes main valve means mounted above said cylinder for forward and rearward movement between a first position communicating the upper end of said drive chamber with said reservoir to effect the drive stroke of said drive piston and a second position communicating the upper end of said drive chamber with the atmosphere to permit said drive piston to move through its return stroke, means defining a pilot chamber, said main valve means having a pilot pressure element movable therewith within said pilot chamber in response to predetermined changes of air pressure within said pilot chamber, manually controlled valve means movable in response to manual actuating from an inoperative position communicating said pressure chamber with the atmosphere into an operative position communicating said pressure chamber with said reServoir to effect the operative stroke of said pressure member and said clincher arm, and sequencing means operable in response to the establishment of a predetermined pressure condition within said pressure chamber following the communication thereof with said reservoir for effecting a change in the air pressure within said pilot chamber sufficient to effect movement of said main valve means into said first position to thereby effect the drive stroke of said drive piston in sequential relation with respect to the operative stroke of said clincher arm.
 7. A device as defined in claim 6 wherein main valve means is movable into said first position in response to the exhaust of air pressure within said pilot chamber to atmosphere and into said second position in response to the establishment of a predetermined elevated air pressure therein, said sequencing means including sequencing valve means operable in one position to exhaust said pilot chamber and in another position to permit the establishment of said predetermined pressure therein, means defining a sensing chamber continuously communicating with said pressure chamber, said sequencing valve means having a pressure element movable within said sensing chamber in one direction to move said sequencing valve means into said one position in response to the establishment of an air pressure substantially equal to reservoir pressure within said pressure chamber and in the opposite direction to move said sequencing valve means into said other position in response to the exhausting of said pressure chamber to atmosphere.
 8. A device as defined in claim 7 wherein said pilot chamber and said sensing chamber are cylindrical and disposed in spaced relation on a common axis which extends rearwardly.
 9. A device as defined in claim 8 wherein said sensing chamber includes a fixed inner wall through which said sensing chamber is communicated with said pressure chamber, the pressure element being in the form of a piston having one side disposed in opposed relation to said inner wall and defining said sensing chamber therebetween and a piston rod extending from the other side of said piston, fixed wall means enclosing an annular space bounded by the exterior of said piston rod and the outwardly extending portion of said piston, and means for continuously communicating said annular space with said reservoir. 